Iron is an essential element for humans and physiological needs are determined by obligatory loss, growth, menstruation and pregnancy. Although iron metabolism occurs in a ‘closed circuit’, physiological losses occur and they must be made good. Three factors are important in the study of iron needs: the total amount of iron in the diet; the nature of the iron compound; and other components of the diet (Hallberg et al. 1998). Although iron de®ciency ensues if insu¾cient iron is absorbed to meet requirement, the total iron absorbed normally exceeds requirement (Hallberg et al. 1997; Jackson, 1997).